Seeking Assistance with PrediXcan Prediction

[Dragonfly1108]

Hi,
I am running predict.py at https://github.com/hakyimlab/predixcan_prediction with some bgen files but got this error: Traceback (most recent call last):
File "/public/home/predixcan_prediction_new/predict.py", line 242, in
transcription_matrix.save()
File "/public/home/predixcan_prediction_new/predict.py", line 139, in save
self.D_samples = self.D_file.create_dataset("samples", (self.n_samples,), dtype='S25')
^^^^^^^^^^^
AttributeError: 'TranscriptionMatrix' object has no attribute 'D_file'
If you have any further insights or suggestions on how to resolve the issue, I would be extremely grateful.